To start off, here is an example of the the stages involved
in one of the more complicated areas.

SMOOTH EDGES

The smooth edges you'll see in areas of the image are done
by taking a color that's half way between the color of the
object and the space behind the object, and applying it to
the sharp edges of the foreground object. Sometimes, to
make it smoother, I'd use up to three different shades of
the color for a smoother transition.

TEXTURES

This style of blending was done by first applying the solid
areas of colors, and then clicking. One pixel at a time.
I'm seriously surprised my mouse still works.

These next few textures were made in almost the same way,
by first applying basic colors, and then blending them.
The difference is just in the way it's blended. If you
look closely at the textured shading in the image, you can
probably get the basic idea of how it was done.

I didn't use the airbrush very much, because of its
tendancy to be a little too random. But I did use it in a
few places, either over other textures or by itself.

SHADING

As previously stated, I used shading before I applied
textures. Some areas of the image were done using just
shading and not adding any extra texture.

As you can see in the close up image of the sky, it's not
perfectly smooth, but lines with a slightly varying shade
going across. To do that, all I had to do is change the
hue, saturation, and brightness by 2, slowly working
towards what I had chosen as the final color, putting a
new line across every time I changed the shade etc.

Then, the shapes that were shaded were done the same way,
but shaped into objects instead of just straight lines.

VIDEO GAME CHARACTERS

Kirby, Ness, and Megaman were done by just finding a
screen shot, using a larger square and shaping them like
large pixels. Which of course, requires nearly no skill,
I just liked how they look.
Chrono was just done with some basic drawing and shading.
The Counter Terrorist was done using various techniques
that were previously mentioned.

TEXT

The text was done by just zooming really far in and making
it look as even as I could. The can was particularly hard,
and not as good as I should've done.

The text on the truck was done by just making up letters
as I went along, and making sure they were in the same
style as the previous ones. I made a few varations on
text for that part.

SUMMARY

All together, I basically used those techniques to make
the whole thing. I'm going to probably add some more
later if I feel like it. I'm sure there are typos and
bad punctuation, but I don't care right now, I'll fix
it later.